With the widespread applications of electronic devices, the desire for expanding functions of electronic devices anytime, anywhere and conveniently are increasing. For example, in business applications, a user might wish to expand a keyboard for a tablet and operate the tablet through the keyboard as needed, as well as charging a tablet or a mobile phone. As for a user such as a salesman, sometimes it desirable to expand a projecting means for electronic devices such as a tablet, a mobile phone, etc. to project the content therein to a screen.
Therefore, there is a need of providing a portable function-expanding device for an electronic device to solve the above problem in the prior art.